Emoncms My Solar app: howto


I got a SDM630 to measure my household and a SDM120 to measure my PV production, eg:

  • pv;P (in W) is my PV/solar production and only negative
  • pv:Ep (in kWh) is the cumulative, positive electricity/energy production.
  • household:P (in W) is negative on export, positive on import
  • household:Ei (in kWh) is the cumulative, positive electricity on import
  • household:Ee (in kWh) is the cumulative, positive electricity on export

I want to configure ‘My Solar’ App in emoncms and I need USE, solar:P, use_kWh, solor_kWh, import_kWh, but I’m not sure how to configure it and what feeds I’m still missing or what feed I should make positive or negative.

Personally I define:

  • Eh: what my house uses, could be imported, could be from solar production or a combination
  • Ei: what is imported from the grid
  • Ee: what is exported to the grid
  • Ep: the production from my solar panels
  • Ed: direct use from my solar in our household and so not exported
  • So Eh=Ei + Ep - Ee
  • And so Ed = Ep - Ee

The values above are all in kWh and are positive values. Of course there are corresponding P values (in W).

I think you need the following mapping for the My Solar App inputs you specified (assuming your Power feeds are named as per your Energy feeds but replacing ‘E’ with ‘P’):
Use → Ph
solar:P → Pp
use_kWh → Eh
solar_kWh → Ep

The convention used is generally: imported Power is positive, exported Power is negative.

Thank you @Greebo. I probably still made a mistake.

My settings:

My Solar (Solar should be > 0.00 kWh):

My graphs:

The App expects all of the values to be positive, with the exception of “import_kwh”, which is expected to be positive for Import and negative for Export.
All of the Energy values are cumulative over all time as well.

Here’s my App settings:

And here’s the equivalent graphs (excluding the Energy totals for Generation and Consumption):

And the Generation and Consumption graphs:

For my brains cumaltive-import-kWh (the red graph) could only go up. Suppose:

  • 1-2 o’clock: an import of 1 kWh
  • 2-3 o’clock: an export of 1 kWh (which is different electricity than the one that is exported as it wasn’t stored)
  • 3-4 o’clock: an import of 0,5 kWh

My personal conclusion would be that cumaltive-import-kWh is 1,5 kWh and not 0,5 kWh. And the grid was used for a total of 2,5 kWh. But apparently that is not how the app works…

I was just answering your question about what the App is expecting.

I personally have two additional feeds that I’ve called “Import Only” and “Export Only” which align with your thinking. My “Import Only” feed only increments while I’m importing and the “Export Only” feed only increments while I’m exporting. Neither of those are used by the “My Solar” App though :slight_smile:

What you write is correct, but I think most of us here would say that number is not Grid Use. Maybe the overall energy transfer via the grid was 2.5 kWh, but that is only rarely a useful piece of information (the only time I think that might be useful would be in calculating the temperature rise of cables and switchgear). By our usual definition, Grid Use is the energy used in the house that was taken from the grid, in your example 1.5 kWh. Total use would be this 1.5 kWh plus the energy from your private generation that was not exported.